Donken R, Dobson SRM, Marty KD, et al. - Based on immunobridging studies, a 2-dose (2D) human papillomavirus (HPV) vaccination schedule has been implemented for adolescents in several countries. Researchers here examined the immunogenicity of 2D vs 3-dose (3D) schedules of the quadrivalent vaccine (4vHPV) up to 10 years after the first dose. They randomized girls aged 9–13 years to receive 2D or 3D and compared these girls with women aged 16–26 receiving 3D at day 1 and months 7, 24, and 120 after the first dose. The competitive Luminex immunoassay (cLIA) and total immunoglobulin G assay were used to determine antibody levels for HPV6/11/16/18. comparison was performed of geometric mean titers (GMTs) and seropositivity rates between the different groups at different time points. For analysis, they used data from 35 2D girls, 38 3D girls, and 30 3D women at 120 months. Outcomes revealed non inferiority of GMTs for HPV6/11/16/18 after 2D or 3D of 4vHPV in girls relative to 3D in adult women up to 120 months postvaccination. This study thereby establishes that the 2D HPV vaccine schedule has long-term immunogenicity.